Thermostatic cut-out for electric circuits.



W. P. HOPFMANN.

THERMOSTATIO GUT-OUT FOB ELECTRIC CIRCUITS.

APPLIOATION FILED mm: 18, 1912.

1,096,915. Patented May 19, 1914.

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WILLIAM F. HOFFMANN, OF DETROIT, MICHIGAN, ASSIGNOR TO FRANK KUHN, 0F

' DETROIT, MICHIGAN.

Specification of Letters Patent.

Patented May 19, 1914.

Application filed June 18, 1912. Serial No. 704,303.

To all whom it may concern Be it known that I, WILLIAM F. HOFFMANN, a citizen of the United States of America, residing at Detroit, in the county of WVayne and State of Michigan, have invented certain new and useful Improvements in Thermostatic Cut-Outs for Electric Circuits, of which the following is a specification, reference being had therein to the accompanying drawings.

The invention relates to cut-outs for electric circuits, and it is the object of the invention to obtain a construction which may be arranged in small space and which will positively operate to open the circuit upon a slight abnormal rise in temperature.

Specifically the construction is devised for use in electrically heated warming pads and in similar devices where it is essential to prevent a rise in temperature without regard to the volume of current that flows through the resistor.

With these objects in view the invention consists in the construction as hereinafter set forth.

In the drawings: Figure 1 is an elevation of a portion of an electric warming pad to which my improved cut-out is applied. Fig. 2 is an enlarged longitudinal section therethrough. Fig. 3 is a similar view showing the open circuit position.

A is a metal bar or case which is provided with a central laterally bent portion B.

C is a resilient tongue member which is secured to one end of the bar A by suitable means such as the clamping bolt D, and which when released from tension will assume the position shown in Fig. 3, where its free end is deflected laterally within the bent portion B of the bar A.

E is a member secured to the opposite end of the bar A but insulated therefrom'by suitable means such as the interposed mica or other insulation F, and G is an insulated clamping bolt for securing said member E. The members E and C overlap each other and normally are attached by a low fusing solder indicated at H. The member E is sufficiently rigid to hold the member C against the tension thereof, so that the parts will normally assume the relation shown in Fig. 2. The device is then connected into the circuit by attaching one of the leads to the bar A, as shown at I, and the other lead to the bar E, as shown at J. Thus the circuit is completed through the connection between said bars E and C.

In use, the device is placed in proximity to the heating resistor as indicated in Fig. 1, so that the heat generated in said resistor will be transmitted to the metallic parts of the controller. As long as the temperature remains below the fusing point of the solder, which attaches the parts E and O, the circuit will be maintained, but a rise of temperature above said fusing point will release the member C, which, by reason of its resiliency and the stress to which it is subjected, will snap out of contact with the member E, assuming the position shown in Fig. 3. This operation not only breaks the circuit but does so quickly so as to avoid arcing. The clearance provided by the lateral bend in the bar A is sufficient for the proper spacing of the separated contacts and at the same time the whole structure may be placed within small space limits and will lie flat against the pad or other device to which it is applied.

What I claim as my invention is:

1. An automatic cut-out for electric circuits, comprising a rigid member having a central portion shaped to provide a lateral chamber, two members mounted upon said rigid member having overlapping portions opposite said lateral chamber, means for insulating one of said members from said rigid member, and a fusible adhesive for attaching the overlapping portions of said members and holding the same in conducting re lation to each other, one of said members being resilient and under a tension to deflect the same laterally from the other member and within said chamber upon the fusing of said adhesive.

2. An automatic cut-out for electric circuits, comprising a rigid bar having a laterally-deflected central portion shaped to form a chamber, two members attached to the opposite end portions of said bar projecting inward therefrom and overlapping each other opposite said chamber, means for insulating one of said members from said rigid member, and a fusible adhesive uniting the In testimony whereof I afiix my signature overlapplng ends of sald members and hold- 1n presence oi two wltnesses.

in the same in electrical conductin relatid n, one of said members being resilie nt and WILLIAM HOFFMANN' 5 under a tension to be laterally deflected With- WVitnesses:

in said chamber upon the fusing of said ad- HARRY W. LUYCK,

hesive. GEORGE S. TOWAR.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents, Washington, D; G. 

